Medical applications of shape memory alloys

Shape memory alloys (SMA) are materials that have the ability to return to a former shape when subjected to an appropriate thermomechanical procedure. Pseudoelastic and shape memory effects are some of the behaviors presented by these alloys. The unique properties concerning these alloys have encouraged many investigators to look for applications of SMA in different fields of human knowledge. The purpose of this review article is to present a brief discussion of the thermomechanical behavior of SMA and to describe their most promising applications in the biomedical area. These include cardiovascular and orthopedic uses, and surgical instruments.

First-principles study on electronic and structural properties of Cu(In/Ga)Se alloys for solar cells

Thin-film photovoltaic solar cells based on the Cu(In1−xGax)Se2 (CIGS) alloys have attracted more and more attention due to their large optical absorption coefficient, long term stability, low cost, and high efficiency. Modern theoretical studies of this material with first-principles calculations can provide accurate description of the electronic structure and yield results in close agreement with experimental values, but takes a large amount of calculation time. In this work, we use first-principles calculations based on the computationally affordable meta- generalized gradient approximation of the density-functional theory to investigate electronic and structural properties of the CIGS alloys. We report on the simulation of the lattice parameters and band gaps, as a function of chemical composition. The obtained results were found to be in a good agreement with the available experimental data.

Adenovirus-mediated siRNA targeting TNF-α and overexpression of bone morphogenetic protein-2 promotes early osteoblast differentiation on a cell model of Ti particle-induced inflammatory response in vitro

Wear particles are phagocytosed by macrophages and other inflammatory cells, resulting in cellular activation and release of proinflammatory factors, which cause periprosthetic osteolysis and subsequent aseptic loosening, the most common causes of total joint arthroplasty failure. During this pathological process, tumor necrosis factor-alpha (TNF-α) plays an important role in wear-particle-induced osteolysis. In this study, recombination adenovirus (Ad) vectors carrying both target genes [TNF-α small interfering RNA (TNF-α-siRNA) and bone morphogenetic protein 2 (BMP-2)] were synthesized and transfected into RAW264.7 macrophages and pro-osteoblastic MC3T3-E1 cells, respectively. The target gene BMP-2, expressed on pro-osteoblastic MC3T3-E1 cells and silenced by the TNF-α gene on cells, was treated with titanium (Ti) particles that were assessed by real-time PCR and Western blot. We showed that recombinant adenovirus (Ad-siTNFα-BMP-2) can induce osteoblast differentiation when treated with conditioned medium (CM) containing RAW264.7 macrophages challenged with a combination of Ti particles and Ad-siTNFα-BMP-2 (Ti-ad CM) assessed by alkaline phosphatase activity. The receptor activator of nuclear factor-κB ligand was downregulated in pro-osteoblastic MC3T3-E1 cells treated with Ti-ad CM in comparison with conditioned medium of RAW264.7 macrophages challenged with Ti particles (Ti CM). We suggest that Ad-siTNFα-BMP-2 induced osteoblast differentiation and inhibited osteoclastogenesis on a cell model of a Ti particle-induced inflammatory response, which may provide a novel approach for the treatment of periprosthetic osteolysis.

Weldability of high strength aluminium alloys

The need for reduced intrinsic weight of structures and vehicles in the transportation industry has made aluminium research of interest. Aluminium has properties that are favourable for structural engineering, including good strength-to-weight ratio, corrosion resistance and machinability. It can be easily recycled saving energy used in smelting as compared to steel. Its alloys can have ultimate tensile strength of up to 750 MPa, which is comparable to steel. Aluminium alloys are generally weldable, however welding of high strength alloys like the 7xxx series pose considerable challenges. This paper presents research on the weldability of high strength aluminium alloys, principally the 7xxx series. The weldability with various weld processes including MIG, TIG, and FSW, is discussed in addition to consideration of joint types, weld defects and recommendations for minimizing or preventing weld defects. Experimental research was carried out on 7025-T6 and AW-7020 alloys. Samples were welded, and weld cross sections utilized in weld metallurgy studies. Mechanical tests were carried out including hardness tests and tensile tests. In addition, testing was done for the presence of Al2O3 on exposed aluminium alloy. It was observed that at constant weld heat input using a pulsed MIG system, the welding speed had little or no effect on the weld hardness. However, the grain size increased as the filler wire feed rate, welding current and welding speed increased. High heat input resulted in lower hardness of the weld profile. Weld preheating was detrimental to AW- 7020 welds; however, artificial aging was beneficial. Acceptable welds were attained with pulsed MIG without the removal of the Al2O3 layer prior to welding. The Al2O3 oxide layer was found to have different compositions in different aluminium alloys. These findings contribute useful additional information to the knowledge base of aluminium welding. The application of the findings of this study in welding will help reduce weld cost and improve high strength aluminium structure productivity by removing the need for pre-weld cleaning. Better understanding of aluminium weld metallurgy equips weld engineers with information for better aluminium weld design.

天父上帝言題皇詔Tian fu shang di yan ti huang zhao.Décrets et pièces diverses publiés par les Tai ping.

Recueil de 13 pièces officielles de la rébellion, datées de 1851, 1852, 1853, avec une table.

乾坤體義Qian kun ti yi.Principes du système du monde.

Cat. imp., liv. 106, f. 16 (en 2 livres).Par le P. Ricci (1552-1610). Texte relatif à la cosmographie et à la géographie, avec figures.

天主一體三位論Tian zhu yi ti san wei lun.

Traité de la Sainte Trinité.Par le P. Monteiro.9 feuillets.

三位一體說San wei yi ti shuo ; alias : 三一聖學San yi sheng xue.

Traité de la Sainte Trinité.Attribué au P. Buglio ; préface sans signature ni date.47 sections.

提正編Ti zheng bian.

Considérations sur les mystères de la foi.Par le P. Jérôme de Gravina, Jésuite (1603-1662 ; noms Chinois Jia Yi mu Jiu zhang). Gravé à l'église de Hai yu avec l'autorisation du P. Simon da Cunha, Jésuite (1587-1660 ; noms Chinois Qu Xi man Fu yi). Préface (1659) par Tong Guo qi, de Dai yuan.6 livres.

聖體要理Sheng ti yao li.

Même ouvrage avec l'autorisation du P. Furtado ; le titre indique la date de 1644 et l'église Ji shan. Vraisemblablement reproduction moderne. La dernière section du livre 2 est supprimée.

聖體荅疑Sheng ti da yi.

Réponse aux doutes sur l'Eucharistie.Par le P. Verbiest. Table et texte.11 feuillets.

聖體仁愛經規條Sheng ti ren ai jing gui tiao.

Exercices et règlement pour la confrérie du Saint Sacrement.Par le P. de Mailla ; préface (1719) et postface de l'auteur. Table. Édition de l'église Shou shan, à Pékin.52 feuillets.

聖體會規Sheng ti hui gui.

Règlement de la confrérie du Saint Sacrement.13 feuillets.

聖體問荅Sheng ti wen da.

Instruction dialoguée sur l'eucharistie.6 feuillets.

Pressure dependence of superconductivity in amorphous Ni x Zr 100-x alloys

Pressure variations of the superconducting transition temperature Ic of a series of amorphous NixZr 1 OO-x alloys have been studied under quasmydrostatic pressures upto 8 G Pa. For amorphous samples having Ni-concentration less than 40%, i)Tc/dP is positive in sign and it decreases non linearly with increase in I. whereasdTcldP is negative in sign for Ni concentration of 45%. Comparison with the Hall coefficient (I) and the thermoelectric power (2) results for the same amorphous alloys leads to the conclusion that s-d hybridization nature of the d-band (Nil plays a central role in the sign reversal behaviour. Application of pressures greater than 2 G Pa to Ni20ZrgO led to the formation of a new phase, w-Zr. which retains its form after the pressure is released.